This invention relates to data processing systems. More specifically, the invention is concerned with a data processing system comprising a plurality of units interconnected by a bus, for information transfer between the units. The units may, for example, include data processing units and memory units.
It is conventional in such a system to rely on an acknowledgement signal to indicate that information sent over the bus has been accepted by the receiving unit or units. A disadvantage of this, however, is that it means that each information transfer is essentially a two-way process : information must first propagate from the sender to the receiver, and the acknowledgement signal must then propagate back from the receiver to the sender. Thus, the minimum time for each transfer is at least twice the bus propagation delay time. This restricts the rate of information transfer over the bus.
An object of the present invention is to avoid this limitation inherent in the use of acknowledgement signals.